-rw-r--r-- 547 djbsort-20190516/cpucycles/amd64cpuspeed/cpucycles.c
#include <stdio.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/sysctl.h>
#include "cpucycles.h"
long long cpucycles(void)
{
unsigned long long result;
asm volatile(".byte 15;.byte 49;shlq $32,%%rdx;orq %%rdx,%%rax"
: "=a" (result) :: "%rdx");
return result;
}
long long cpucycles_persecond(void)
{
int oid[2];
int val;
size_t size;
oid[0] = CTL_HW;
oid[1] = HW_CPUSPEED;
size = sizeof val;
if (sysctl(oid,2,&val,&size,0,0) == -1) return 0;
if (size != sizeof val) return 0;
return val * 1000000LL;
}